Embodiments of the present disclosure relate to methods, kits and compositions for two-channel nuclei acid sequencing using blue and violet light excitation (e.g., lasers at 450-460 nm and 400-405 nm respectively). In particular, the nucleotides may be directly labeled with a blue dye, a violet dye, or both a blue dye and a violet dye. Alternatively, one or more nucleotides for incorporation may be unlabeled and affinity reagents containing a blue dye, a violet dye, or both a blue dye and a violet dye may be used to bind specifically to each type of nucleotides incorporated.